• Proceedings of the IEEK Conference
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• summer
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• pp.204-208
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• 2004

Embedded business will be expanded market more and more since customers seek more wearable and ubiquitous systems. Cellular telephones, PDAs, notebooks and portable multimedia devices could bring higher microprocessor revenues and more rewarding improvements in performance and functions. Increasing battery capacity is still creeping along the roadmap. Until a small practical fuel cell becomes available, microprocessor developers must come up with power-reduction methods. According to MPR 2003, the instruction and data caches of ARM920T processor consume $44\%$ of total processor power. The rest of it is split into the power consumptions of the integer core, memory management units, bus interface unit and other essential CPU circuitry. And the relationships among CPU, peripherals and caches may change in the future. The processor working on higher operating frequency will exact larger cache RAM and consume more energy. In this paper, we propose advanced low power trace cache which caches traces of the dynamic instruction stream, and reduces cache access times. And we evaluate the performance of the trace cache and estimate the power of the trace cache, which is compared with conventional cache.

• Korean Journal of Cognitive Science
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• v.19 no.1
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• pp.57-74
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• 2008

This study aimed to investigate the preferential brain activations involed in the set size during random number generation (RNG). The BNG condition gave more increased activations in the anterior cingulate cortex (ACC), inferior frontal gyrus (IFG), inferior parietal lobule (IPL), and superior temporal gyrus (STG) than the simple counting condition, which was a control rendition. When the activations were compared by the small set size condition versus the large set size condition, broad areas covering tempore-occipital network, ACC, and postcentral gyrus were more highly activated in the small set size condition than in the large set size condition, while responses of areas including medial frontal gyrus, superior parietal lobule, and lingual gyrus were more increased in the large set size condition than in the small set size condition. The capacity hypothesis of working memory fails to explain the results. On the contrary, strategy selection hypothesis seems to explain the current observations properly.

• Korean Journal of Cognitive Science
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• v.13 no.4
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• pp.91-98
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• 2002

The aim of this study is to make the recall-based reading span test(Daneman & Carpenter, 1980) into the recognition-based test for on-line measuring the capacity of the participant. In order to measure the concurrent validity, a series of experiments is performed with varying features of distractors consisting of the reading span test. In experiment 1, which included irrelevant words as distractor, low correlation was observed. And in experiment 2, including several types of distractors which interfere with the selection of target words, low correlation was observed too. But in experiment 3, including distractors no more relevant in the Present trial but relevant in previous trial, high correlation was observed. The results of this study have theoretical implications on the validity of the reading span test and practical implication in that this study provides the tool for the studies on individual differences in working memory capacity.

• Phonetics and Speech Sciences
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• v.10 no.3
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• pp.1-8
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• 2018

The vowel /o/ in Seoul Korean has been undergoing a sound change by altering the acoustic weighting of F2 and F1. Studies documented that this on-going change redefined the nature of a /o/-/u/ contrast as F2 differences rather than as F1 differences. The current study examined two cognitive factors namely executive function capacity (EF) and autistic traits, in terms of their roles in explaining who in speech community would adapt new acoustic forms of the target vowels, and who would retain the old forms. The participants, 55 college students speaking Seoul Korean, produced /o/ and /u/ vowels in isolated words; and completed three EF tasks (Digit N-Back, Stroop, and Trail-Making Task), and an Autism screening questionnaire. The relationships between speakers' cognitive task scores and their utilizations of F1 and F2 were analyzed using a series of correlation tests. Results yielded a meaningful relationship in participants' EF scores interacting with gender. Among the females, speakers with higher EF scores were better at retaining F1, which is a less informative cue for females since they utilized F2 more than they did F1 in realizing /o/ and /u/. In contrast, better EF control among male speakers was associated with more use of the new cue (F2) where males still utilized F1 as much as F2 in the production of /o/ and /u/ vowels. Taken together, individual differences in acoustic realization can be explained by individuals' cognitive abilities, and their progress in the sound change further predicts that cognitive ability influences the utilization of acoustic information which is non-primary to the speaker.

• Science of Emotion and Sensibility
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• v.20 no.2
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• pp.127-136
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• 2017

Attentional blink is observed in an identification task of multiple targets during rapid serial visual presentation (RSVP) where performance for the second target (T2) that follows within 500ms of the first (T1) shows systematic decrease although that for T1 remains highly accurate. Theories accounting for attentional blink can be classified into two broad categories of resource depletion model and disruption of input filter model. Meanwhile, visual attention capacity shows hemifield independence between left and right visual fields, and many studies reported bilateral advantage in a range of visual working memory tasks. The current research tested two major theories of attentional blink using bilateral independence of attentional capacity. To this end, we conducted two experiments where two RSVPs were presented in either bilateral or unilateral visual fields. Experiment 1 presented two RSVPs which contained both T1 and T2 in either bilateral or unilateral visual fields and tested interaction between attentional blink and bilateral advantage. Experiment 2 removed T1 in one of the two RSVPs to test whether attentional blink obtains when identification of T1 and T2 utilize independent sources of attention across two visual fields. The results showed that subjects were more accurate when two RSVPs were presented in bilateral visual fields (i.e., bilateral advantage) although there was no interaction between attentional blink and bilateral advantage (Experiment 1). In addition, attentional blink for T2 was observed in a T1-absent RSVP even when two RSVPs were presented in bilateral visual fields (Experiment 2). These results support disruption of input filter model rather than resource depletion model.

• Korean Journal of Cognitive Science
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• v.20 no.2
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• pp.125-154
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• 2009

This paper describes the possibility of human physiological data, especially brain-wave activity, to detect cognitive overload, a phenomenon that may occur while learner uses an e-learning system. If it is found that cognitive overload to be detectable, providing appropriate feedback to learners may be possible. To illustrate the possibility, while engaging in cognitive activities, cognitive load levels were measured by EEG (electroencephalogram) to seek detection of cognitive overload. The task given to learner was a computerized listening and recall test designed to measure working memory capacity, and the test had four progressively increasing degrees of difficulty. Eight male, right-handed, university students were asked to answer 4 sets of tests and each test took from 61 seconds to 198 seconds. A correction ratio was then calculated and EEG results analyzed. The correction ratio of listening and recall tests were 84.5%, 90.6%, 62.5% and 56.3% respectively, and the degree of difficulty had statistical significance. The data highlighted learner cognitive overload on test level of 3 and 4, the higher level tests. Second, the SEF-95% value was greater on test3 and 4 than on tests 1 and 2 indicating that tests 3 and 4 imposed greater cognitive load on participants. Third, the relative power of EEG gamma wave rapidly increased on the 3rd and $4^{th}$ test, and signals from channel F3, F4, C4, F7, and F8 showed statistically significance. These five channels are surrounding the brain's Broca area, and from a brain mapping analysis it was found that F8, right-half of the brain area, was activated relative to the degree of difficulty. Lastly, cross relation analysis showed greater increasing in synchronization at test3 and $4^{th}$ at test1 and 2. From these findings, it is possible to measure brain cognitive load level and cognitive over load via brain activity, which may provide atimely feedback scheme for e-learning systems.